The present invention relates to chair bases, and more particularly to a chair base with radially extending legs and a hub that is adapted to support a pedestal-type chair.
Chair bases with radially extending, castored legs are often used to support mobile office chairs. Castors are supported at the outer end of each leg, and the inner end of the legs are welded to a tubular sleeve-like center hub to form a "spider frame" base frame. The result is that the legs and the center hub undergo considerable cantilever-type stress when loaded by a person sitting in the chair. Spider-frame base constructions are desired that minimize the number and cost of parts and pieces, yet that provide adequate strength to support both the individual load that occurs from a seated user and a chair, and to provide optimal distribution of stress to support cyclical loading that occurs from repeated use. Often, relatively minor shape changes can result in significant advantages in stress distribution and can aid the manufacturing processes.
U.S. Pat. No. 5,906,343 discloses a chair base where tubular legs having a rectangular cross-sectional shape are welded to a sleeve-type center hub by top and bottom ring welds. In U.S. Pat. No. 5,906,343, the sidewalls are not welded together, but instead are abutted against each other and against the hub in a manner that stabilizes each other. A potential problem is that the dimension between opposing sidewalls of the tubular legs in U.S. Pat. No. 5,906,343 must be closely controlled. Otherwise, the space remaining for the "last" tubular leg that is to be arranged against the center hub between the other tubular legs (i.e., prior to welding) will be problematic. Specifically, if the remaining space is too small, the "last" tubular leg will interferingly engage other tubular legs and will not fit against the hub. On the other hand, if the remaining space is too large, the "last" tubular leg will not fit snugly into the remaining space, such that at least one of the sidewalls will not abut the sidewalls of the adjacent tubular legs.
Accordingly, a chair base solving the aforementioned problems is desired.